1. Field of the Invention
The present invention relates to a method for the manufacture of a semiconductor device which has at least a non-single-crystal semiconductor layer, transparent or nontransparent conductive layer, or laminate member composed of transparent and nontransparent conductive layers, such as a semiconductor photoelectric conversion device, field effect transistor or the like, and more particularly to improvement in a semiconductor device manufacturing method which includes at least a step of forming a non-single-crystal semiconductor layer, transparent or nontransparent conductive layer, or laminate member composed of transparent and nontransparent conductive layers by patterning with a laser beam.
2. Description of the Prior Art
Heretofore there has been proposed a semiconductor device manufacturing method which includes at least a step of forming a non-single-crystal semiconductor layer, transparent or nontransparent conductive layer, or laminate member composed of transparent and nontransparent conductive layers by patterning with a laser beam.
Compared with another manufacturing method which employs a photolithography technique for the formation of such a layer, the abovesaid method excels in that the layer can be formed without any defects. The reason for this is that in the case of forming the layer by photolithography, a photoresist mask therefor is prone to pinholing or exfoliation at its marginal edges, which results in the formation of defects, whereas the method utilizing the patterning process with a laser beam has no such factors which cause defects.
With the conventional method employing the patterning technique with a laser beam for the formation of the non-single-crystal semiconductor layer, transparent or nontransparent conductive layer, or laminate member composed of transparent and non-transparent conductive layers, it is a general practice to use a YAG laser which emits a laser beam having a relatively long wavelength of about 1060 nm.
The absorption coefficient of the abovesaid layer for the laser beam of such a relatively long wavelength is extremely low. For example, the absorption coefficient of a non-single-crystal silicon layer is 10.sup.3 /cm or so. In consequence, the laser beam enters very deeply into the non-single-crystal semiconductor layer, transparent or nontransparent conductive layer, or laminate member. For instance, the penetration depth of such a laser beam into the non-single-crystal semiconductor layer is approximately 10 .mu.m at a depth where the light intensity is 1/e (where e is nearly equal to 2.72) of the light intensity on the surface of the layer, and around 1000 .mu.m at a depth where the light intensity is 1/100 of the light intensity on the layer surface.
Accordingly, when the non-single-crystal semiconductor layer, the transparent or nontransparent conductive layer, or laminate member is as thin as 1 .mu.m or less, it is feared that a substrate and other layers underlying it is damaged or patterned. Also it is feared that the marginal edges of the non-single-crystal semiconductor layer, transparent or non-transparent conductive layer, or laminate member are swollen or exfoliated.
Furthermore, in the case of the laser beam having such a relatively long wavelength of 1060 nm or so, it is difficult to reduce its minimum spot diameter to a small value of 100 .mu.m or less. Therefore, difficult, with the conventional manufacturing method, to finely form the non-single-crystal semiconductor layer, transparent or nontransparent conductive layer, or laminate member with high precision. In addition, in the case of simultaneously forming a plurality of non-single-crystal semiconductor layers, transparent or nontransparent conductive layers, or laminate members, they cannot be spaced apart a small distance of 100 .mu.m or less. This imposes severe limitations on the fabrication of a small and compact semiconductor device having a plurality of non-single-crystal semiconductor layers, transparent or nontransparent conductive layers, or laminate members.